package com.ybg.mq.util;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class MD5 {
	
	private static final Logger				log		= LogManager.getLogger();
	private static char[]					digits	= { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
	private static Map<Character, Integer>	rDigits	= new HashMap<Character, Integer>(16);
	static {
		for (int i = 0; i < digits.length; ++i) {
			rDigits.put(digits[i], i);
		}
	}
	private static MD5			me		= new MD5();
	private MessageDigest		mHasher;
	private final ReentrantLock	opLock	= new ReentrantLock();
	
	private MD5() {
		try {
			this.mHasher = MessageDigest.getInstance("md5");
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	public static MD5 getInstance() {
		return me;
	}
	
	public String getMD5String(String content) {
		return this.bytes2string(this.hash(content));
	}
	
	public String getMD5String(byte[] content) {
		return this.bytes2string(this.hash(content));
	}
	
	public byte[] getMD5Bytes(byte[] content) {
		return this.hash(content);
	}
	
	public byte[] hash(String str) {
		this.opLock.lock();
		try {
			byte[] bt = this.mHasher.digest(str.getBytes("utf-8"));
			if (null == bt || bt.length != 16) {
				throw new IllegalArgumentException("md5 need");
			}
			return bt;
		} catch (UnsupportedEncodingException e) {
			throw new RuntimeException("unsupported utf-8 encoding", e);
		} finally {
			this.opLock.unlock();
		}
	}
	
	public byte[] hash(byte[] data) {
		this.opLock.lock();
		try {
			byte[] bt = this.mHasher.digest(data);
			if (null == bt || bt.length != 16) {
				throw new IllegalArgumentException("md5 need");
			}
			return bt;
		} finally {
			this.opLock.unlock();
		}
	}
	
	public String bytes2string(byte[] bt) {
		int l = bt.length;
		char[] out = new char[l << 1];
		for (int i = 0, j = 0; i < l; i++) {
			out[j++] = digits[(0xF0 & bt[i]) >>> 4];
			out[j++] = digits[0x0F & bt[i]];
		}
		if (log.isDebugEnabled()) {
			log.debug("[hash]" + new String(out));
		}
		return new String(out);
	}
	
	public byte[] string2bytes(String str) {
		if (null == str) {
			throw new NullPointerException("Argument is not allowed empty");
		}
		if (str.length() != 32) {
			throw new IllegalArgumentException("String length must equals 32");
		}
		byte[] data = new byte[16];
		char[] chs = str.toCharArray();
		for (int i = 0; i < 16; ++i) {
			int h = rDigits.get(chs[i * 2]).intValue();
			int l = rDigits.get(chs[i * 2 + 1]).intValue();
			data[i] = (byte) ((h & 0x0F) << 4 | l & 0x0F);
		}
		return data;
	}
	
	public static void main(String[] args) {
		System.out.println(MD5.getInstance().getMD5String("123456"));
	}
}
